Water-metachromatic laminate, and process for its production

ABSTRACT

On a support, a porous resin layer which is opaque in a water-unabsorbed state and capable of turning transparent in a water-absorbed state is formed, and also a water-repellent resin layer is so provided as to exist in the porous resin layer at its some area or areas in a co-existent state, to make up a water-metachromatic laminate. A novel toy element can be provided in which latent images standing invisible in a normal condition are rendered visible by means of water as a medium so as to be visually distinguished.

[0001] This application claims the benefit of Japanese Patentapplications No. 2000-174140 and No. 2000-329827 which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a water-metachromatic laminate and aprocess for its production. More particularly, it relates to awater-metachromatic laminate in which an image standing latent in anormal condition is rendered visible by means of water as a medium so asto be visually distinguished, and a process for its production.

[0004] 2. Related Background Art

[0005] Coated papers or sheets comprising a support and laminatedthereto a porous resin layer containing a low-refractive-index pigment,into the porous resin layer of which a liquid such as water is absorbedto make it transparent to cause a background color tone to appear, aredisclosed in the past (e.g., Japanese Patent Publications No. 50-5097and No. 5-15389).

SUMMARY OF THE INVENTION

[0006] An object of the present invention is to provide awater-metachromatic laminate in which, utilizing the properties of theabove porous resin layer, latent images standing invisible in a normalcondition are rendered visible by means of water as a medium so as to bevisually distinguished, and to be usable as a toy and enjoyable inunexpectedness, decorativeness and detectability so that it isapplicable to a variety of fields of toys, doll clothing, teachingmaterials, picture books, picture coloring, artificial flowers,clothing, swimsuit, umbrellas, raincoats, rainproof shoes and otherrainware, and to provide an effective process for producing such awater-metachromatic laminate.

[0007] To achieve the above object, the present invention provides awater-metachromatic laminate comprising a support and superposinglyprovided thereon i) a porous resin layer which is formed of a binderresin to which a low-refractive-index pigment stands fixed dispersedly,and is opaque in a water-unabsorbed state and capable of turningtransparent in a water-absorbed state and ii) a water-repellent resinlayer so provided as to exist in the porous resin layer at its some areaor areas in a co-existent state; the porous resin layer being so made upthat its area or areas not provided with the water-repellent resin layerturn(s) transparent in a water-absorbed state so that the both layersare visually distinguishable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a vertical sectional illustration of an example of thewater-metachromatic laminate of the present invention.

[0009]FIG. 2 is a vertical sectional illustration of another example ofthe water-metachromatic laminate of the present invention.

[0010]FIG. 3 is a vertical sectional illustration of still anotherexample of the water-metachromatic laminate of the present invention.

[0011]FIG. 4 is a vertical sectional illustration of a further exampleof the water-metachromatic laminate of the present invention.

[0012]FIG. 5 is a vertical sectional illustration of a still furtherexample of the water-metachromatic laminate of the present invention.

[0013]FIGS. 6A and 6B illustrate visual conditions in which the porousresin layer is in FIG. 6A a water-unabsorbed state and FIG. 6B awater-absorbed state in an example of the water-metachromatic laminateof the present invention.

[0014]FIGS. 7A and 7B illustrate visual conditions in which the porousresin layer is in FIG. 7A a water-unabsorbed state and FIG. 7B awater-absorbed state in another example of the water-metachromaticlaminate of the present invention.

[0015]FIGS. 8A and 8B illustrate visual conditions in which the porousresin layer is in FIG. 8A a water-unabsorbed state and FIG. 8B awater-absorbed state in still another example of the water-metachromaticlaminate of the present invention.

[0016]FIGS. 9A and 9B illustrate visual conditions in which the porousresin layer is in FIG. 9A a water-unabsorbed state and FIG. 9B awater-absorbed state in a further example of the water-metachromaticlaminate of the present invention.

[0017]FIGS. 10A and 10B illustrate visual conditions in which the porousresin layer is in FIG. 10A a water-unabsorbed state and FIG. 10B awater-absorbed state in a still further example of thewater-metachromatic laminate of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention is described below with reference to theaccompanying drawings (see FIG. 1 through FIGS. 10A and 10B).

[0019] The present invention is a water-metachromatic laminate 1comprising a support 2 and superposingly provided thereon i) a porousresin layer 3 which is formed of a binder resin to which alow-refractive-index pigment stands fixed dispersedly, and is opaque ina water-unabsorbed state and capable of turning transparent in awater-absorbed state and ii) a water-repellent resin layer 4 so providedas to exist in the porous resin layer 3 at its some area or areas in aco-existent state; the porous resin layer 3 being so made up that itsarea or areas not provided with the water-repellent resin layer 4turn(s) transparent in a water-absorbed state so that the both layers 3and 4 are visually distinguishable.

[0020] In preferred embodiments, at least one of the porous resin layer3 and the water-repellent resin layer 4 may comprise any image or imagesselected from a letter, a mark or sign, an Arabic or Roman numeral, aspot, a line and a design; a colored layer may be provided between thesurface of the support 2 and the porous resin layer 3; another coloredlayer 51 may be provided on the water-repellent resin layer 4; thecolored layer 51 may comprise any image or images selected from aletter, a mark or sign, an Arabic or Roman numeral, a spot, a line and adesign; the low-refractive-index pigment may comprise a fine-particlesilicic acid and the binder resin may be selected from urethane resins;the low-refractive-index pigment may comprise a fine-particle silicicacid produced by a wet process and may be formulated in the porous resinlayer 3 in a proportion of from 1 to 30 g/m²; the support 2 may comprisea cloth; and the cloth may be made water-repellent.

[0021] The present invention is also a process for producing awater-metachromatic laminate, comprising the steps of;

[0022] providing a porous resin layer 3 on a support 2; and

[0023] thereafter applying onto the porous resin layer 3 awater-repelling solution containing a water-repellent resin, by aprinting, coating, spraying, writing or stamping means to make thewater-repelling solution adhere to the porous resin layer 3 andpenetrate thereinto;

[0024] followed by drying to form a water-repellent resin layer 4existing in the porous resin layer 3 in a co-existent state.

[0025] The above support 2 may be in the form of a sheet made of amaterial of various types such as paper, synthetic paper, rubber,plastic, metal (such as aluminum), stone, glass and cloth. Withoutlimitations thereto, cubic or undulating shapes made of variouswater-resistant materials are also effective.

[0026] Incidentally, on the back of the support 2, a general-purposeadhesive used for pressure-sensitive adhesive sheets may be coated sothat it may function as a pressure-sensitive adhesive sheet.

[0027] The low-refractive-index pigment may include fine-particlesilicic acid, baryte powder, precipitated barium sulfate, bariumcarbonate, precipitated calcium carbonate, gypsum, clay, talc, aluminawhite and basic magnesium carbonates. These are pigments having arefractive index in the range of from 1.4 to 1.7 and exhibit goodtransparency upon absorption of water or the like.

[0028] There are no particular limitations on the particle diameter ofthe low-refractive-index pigment. Those having particle diameters offrom 0.03 to 10.0 μm may preferably be used.

[0029] The low-refractive-index pigment may also be used in combinationof two or more types.

[0030] As a low-refractive-index pigment used preferably, it includesfine-particle silicic acid.

[0031] The fine-particle silicic acid is produced as non-crystalline,amorphous silicic acid. According to its production process, it isroughly grouped into a dry-process product obtained by gaseous-phasereaction such as thermal decomposition of a silicon halide such assilicon tetrachloride (hereinafter “dry-process fine-particle silicicacid”) and a wet-process fine-particle silicic acid obtained byliquid-phase reaction such as decomposition of sodium silicate with anacid (hereinafter “wet-process fine-particle silicic acid”). Either maybe used, but the wet-process fine-particle silicic acid is morepreferably used because, when it is used, it has a higher hidingperformance in a normal condition than the system of dry-processfine-particle silicic acid and hence the binder resin can be mixed in alarger proportion to the fine-particle silicic acid to enableimprovement in film strength of the porous resin layer 3 itself.

[0032] As the fine-particle silicic acid used to satisfy the hidingperformance of the porous resin layer 3 in a normal condition, thewet-process fine-particle silicic acid is preferred as stated above.This is because the dry-process fine-particle silicic acid and thewet-process fine-particle silicic acid differ in structure from eachother. The dry-process fine-particle silicic acid forms athree-dimensional structure as shown below in which silicic acid standscombined closely;

[0033] whereas the wet-process fine-particle silicic acid has what iscalled two-dimensional structure moiety as shown below in which silicicacid is condensed to form a long molecular arrangement.

[0034] Thus, the wet-process fine-particle silicic acid has a coarsermolecular structure than the dry-process fine-particle silicic acid, andhence, when used in the porous resin layer, the wet-processfine-particle silicic acid can provide superior irregular lightreflection properties in a dried state compared with a system making useof the dry-process fine-particle silicic acid, thus bringing about agreat hiding performance in a normal condition, as so presumed.

[0035] The medium chiefly absorbed in the porous resin layer 3 is water.Accordingly, as the low-refractive-index pigment contained therein, thewet-process fine-particle silicic acid has more hydroxyl groups presenton particle surface as silanol groups than the dry-process fine-particlesilicic acid, and is preferably used because it has an appropriatehydrophilicity.

[0036] In the case when the wet-process fine-particle silicic acid isused as the low-refractive-index pigment, in order to satisfy both thehiding performance in normal condition and the transparency inliquid-absorbed condition, it may preferably be in a coating weight offrom 1 g/m² to 30 g/m², and more preferably from 5 g/m² to 20 g/m²,which may depend on the type of the wet-process fine-particle silicicacid and its properties such as particle diameter, specific surface areaand oil absorption. If it is less than 1 g/m², it is difficult to obtaina sufficient hiding performance in normal condition. If on the otherhand it is more than 30 g/m², it is difficult to obtain a sufficienttransparency in liquid-absorbed condition.

[0037] The low-refractive-index pigment is dispersed in a vehiclecontaining a binder resin as a binding agent, to form a dispersion ink,which is then coated on the surface of the support 2 by a means such asprinting, coating or spraying to form the porous resin layer 3.

[0038] The binder resin may include urethane resins, nylon resins, vinyacetate resins, acrylate resins, acrylate copolymer resins, acryl polyolresins, vinyl chloride-vinyl acetate copolymer resins, maleic acidresins, polyester resins, styrene resins, styrene copolymer resins,polyethylene resins, polycarbonate resins, epoxy resins,styrene-butadiene copolymer resins, acrylonitrile-butadiene copolymerresins, methyl methacrylate-butadiene copolymer resins, butadieneresins, chloroprene resins, melamine resins, and emulsions of theseresins, as well as casein, starch, cellulose derivatives, polyvinylalcohol, urea resins, and phenolic resins.

[0039] In particular, it is effective to use urethane resins, or resinsincorporated at least with urethane resins.

[0040] Incorporation of a urethane resin in the binder resin enablesimprovement in film strength of the porous resin layer 3, thus the layercan be used for various purposes which require durability, and also itshiding performance in dried condition and transparency inliquid-absorbed condition are by no means damaged.

[0041] The urethane resins include polyester type urethane resins,polycarbonate type urethane resins and polyether type urethane resins.Two or more types of these may be used in combination. Also usable areurethane type emulsion resins prepared by emulsifying and dispersing anyof the above resins in water, and colloidal dispersion type (ionomertype) urethane resins dissolved or dispersed in water byself-emulsification without requiring any emulsifier on account of ionicgroups of urethane resin itself (urethane ionomer) having ionicproperties.

[0042] As the above urethane type resins, either of water-solubleurethane resins and oil-soluble urethane resins may be used. Preferablyusable in the present invention are water-soluble urethane resins, inparticular, urethane type emulsion resins and colloidal dispersion typeurethane resins. The urethane resins may be used alone or incombination. Other binder resins may also be used in combination, inaccordance with the material and form of the support 2 or theperformance required in films. In the case when a binder resin otherthan the urethane resin is used, the urethane resin may preferably beincorporated in the binder resin of the porous resin layer 3 in anamount of 30% or more as weight ratio of solid content, in order toattain practical film strength.

[0043] In the porous resin layer 3 thus formed, a conventionally knownmetalescent pigment such as titanium-dioxide-coated mica,iron-oxide/titanium-dioxide-coated mica, iron-oxide-coated mica,guanine, sericite, basic lead carbonate, acid lead arsenate or bismuthoxychloride may be added or a common dye or pigment, a fluorescent dyeor a fluorescent pigment may be mixed so that changes in color can bemade rich in variety. A reversible thermochromic pigment, which iscapable of reversibly changing in color (reversible metachromatism) upontemperature changes, may also be mixed.

[0044] The water-repellent resin layer 4 is a layer which exists in theporous resin layer 3 in a co-existent state, formed by applying onto theporous resin layer 3 a water-repelling solution containing awater-repellent resin, to make the water-repelling solution adhere tothe porous resin layer 3 and penetrate thereinto so as to form an imagein an appropriate form, followed by drying; the water-repellent resinbeing selected from water-repellent resins such as silicon types,paraffin types, polyethylene types, alkylethylene urea types andfluorine types.

[0045] Of the above water-repellent resins, fluorine typewater-repellents are effective in view of water-repellent effect andworking suitability, and may effectively be applied in a coverageranging from 1 g/m² to 50 g/m², and preferably from 2 g/m² to 30 g/m².

[0046] The colored layer 5 is a layer formed directly on the surface ofthe support 2, and is seen through the porous resin layer 3 being in awater-absorbed state, to improve visual effect. The colored layer 5 isby no means limited to a solid-printed layer, and may also comprise anappropriate image. It is also by no means limited to a layer formed of acoloring material containing any general-purpose dye or pigment, and mayalso be a reversible thermochromic layer formed of a coloring materialcontaining a reversible thermochromic material. Incidentally, thesupport 2 itself may be a layer standing colored in which thegeneral-purpose colorant or reversible thermochromic material has beenblended.

[0047] The colored layer 51 provided on the water-repellent resin layer4 functions to make images visible in a greater variety.

[0048] As the above reversible thermochromic material capable ofproviding reversible thermochromic properties, usable is, e.g., areversible thermochromic composition containing three components whichare an electron-donating color-developing organic compound, anelectron-accepting compound and an organic compound medium capable ofcausing the color-developing reaction of the above both compounds totake place reversibly. Also usable are liquid crystal, Ag₂HgI₄, andCu₂HgI₄.

[0049] As the above reversible thermochromic composition containingthree components which are an electron-donating color-developing organiccompound, an electron-accepting compound and an organic compound mediumcapable of causing their color-developing reaction to take placereversibly, it may specifically include those disclosed in JapanesePatent Publications No. 51-35414, No. 51-44706, No. 51-44708, No.52-7764 and No. 1-29398 and Japanese Patent Application Laid-Open No.7-186546. These materials change in color at about a given temperature(color-changing point) making a border, and in the normal temperatureregion can only exist in any one specific state of both states beforeand after their color change. More specifically, these are of a typethat shows what is called a small hysteresis width (ΔH) ontemperature/color density due to changes in temperature to causemetachromatism, in which the other state is maintained so long as theheat or cold that is required for them to come into that state isapplied, but returns to the state shown in the normal temperature regiononce the heat or cold becomes not applied.

[0050] Also effective are those disclosed in Japanese Patent PublicationNo. 4-17154, Japanese Patent Applications Laid-Open No. 7-179777, No.7-33997 and so forth, which have been proposed by the present applicant.These are thermochromic color memorizable compositions that show greathysteresis characteristics to cause metachromatism, i.e., metachromatcimaterials of a type capable of changing in color following courses whichare greatly different in shape of curves formed by plotting changes incoloring density due to changes in temperature, between a case where thetemperature is raised from the side of a temperature lower than acolor-changing temperature region and a case where inversely thetemperature is dropped from the side of a temperature higher than thecolor-changing temperature region, and having a characteristic featureof capable of memorizing a state changed at a low-temperature sidecolor-changing point or below or at a high-temperature sidecolor-changing point, in the normal temperature region between thelow-temperature side color-changing point and the high-temperature sidecolor-changing point.

[0051] The composition may also include, as heat-color-developing typethermochromic compositions, which are capable of developing a color uponheating from the color-extinguished state, systems in which a specificalkoxyphenolic compound having a straight-chain or side-chain alkylgroup having 3 to 18 carbon atoms is used as the electron-acceptingcompound (Japanese Patent Applications Laid-Open No. 11-129623 and No.11-5973) and systems in which a specific hydroxybenzoic ester is used(Japanese Patent Application Laid-Open No. 2001-105732), which have beenproposed by the present applicant.

[0052] The reversible thermochromic composition containing threecomponents which are an electron-donating color-developing organiccompound, an electron-accepting compound and an organic compound mediumcapable of causing their color-developing reaction to take placereversibly as described above can be effective even when used as it is,and may preferably be used as a microcapsule pigment which encloses thecomposition in microcapsules. Namely, this is because the reversiblethermochromic composition can be kept to have the same composition undervarious use conditions and can have the same operation and effect.

[0053] In the case when it is enclosed in microcapsules, a chemicallyand physically stable pigment composition can be made up. Practicalutility can be satisfied when the microcapsules have a particle diameterranging from 0.1 to 50 μm, preferably from 0.1 to 30 μm, and morepreferably from 1 to 20 μm.

[0054] The thermochromic material may be formed into such microcapsulesby conventionally known methods such as interfacial polymerization, insitu polymerization, cure-in-liquid coating, phase separation fromaqueous solution, phase separation from organic solvent, melt-diffusioncooling, air-suspension coating, and spray drying, any of which mayappropriately be selected according to uses. Also, when put intopractical use, the surfaces of the microcapsules may be endowed withdurability according to purposes by further forming secondary resincoatings thereon, or their surface properties may be modified.

[0055] The water-metachromatic laminate 1 of the present inventionoperates as described below, on account of the constituent factorsdescribed above.

[0056] The porous resin layer 3 is opaque in a water-unabsorbed stateand capable of turning transparent in a water-absorbed state, so thataspects of an underlying layer can be seen through that layer. Hence, ina system in which the colored layer 5 is provided as the underlyinglayer, its color or images can be seen, and, in a system in which thecolored layer 5 is not provided, the color of the support itself can beseen. Here, the water-repellent resin layer 4 is so provided as to existin the porous resin layer 3 at its some area or areas in a co-existentstate, and hence the porous resin layer 3 at the area or areas where thewater-repellent resin layer 4 co-exists does not form the water-absorbedstate because of the latter's water-repellent effect, and the opaquestate is kept there. (Since the water-repellent resin layer 4 istransparent, the opaque state of the porous resin layer 3 can beidentified.)

[0057] Thus, the water-repellent resin layer 4 and the porous resinlayer 3 which are hardly distinguishable in a normal condition(water-unabsorbed state), become distinguishable upon absorption ofwater into the porous resin layer 3 at its part where thewater-repellent resin layer 4 is not provided. This change in aspects isinterchangeable.

[0058] The absorption of water into the porous resin layer 3 can beachieved by making any desired portion or portions wet by dipping inwater, spraying of water or by a means such as a writing brush, a brush,a pen or a stamp.

[0059] In a system in which the reversible thermochromic material isused, changes in color caused by changing environmental temperature orby heating or cooling can be seen, making aspects of changes rich invariety.

[0060] The present invention secondly relates to an effective productionprocess for the water-metachromatic laminate 1 described above, and theprocess is characterized by;

[0061] providing the porous resin layer 3 on the support 2; and

[0062] thereafter applying onto the porous resin layer 3 thewater-repelling solution containing a water-repellent resin, by aprinting, coating, spraying, writing or stamping means to make thewater-repelling solution adhere to the porous resin layer 3 andpenetrate thereinto;

[0063] followed by drying to form the water-repellent resin layer 4existing in the porous resin layer 3 in a co-existent state.

[0064] In the foregoing, the printing means may be exemplified by screenprinting, gravure printing and offset printing. In particular, thescreen printing enables relatively easy formation of any desired imagessuch as letters, marks or signs, Arabic or Roman numerals, spots, lines,designs and halftone patterns according to purposes by regulating theopening percentage, pore diameter and line diameter of a screen, and iseffective also in view of the regulation of thickness of thewater-repellent resin layer 4 (i.e., the coating weight of thewater-repelling solution).

[0065] The support used in the present invention is not limited tosheet-shaped one, and all of those having cubic or undulating shapes areeffective. It is not limited to specific sheets shown in the followingExamples.

EXAMPLES

[0066] The present invention will be described below in greater detailby giving Examples. In the following, “part(s)” means “part(s) byweight”.

Example 1

[0067] See FIGS. 1, 6A and 6B

[0068] On the surface of a support 2 comprised of a white broad cloth ofpolyester and cotton (65%:35%) mixed yarn, a fluorescent pink screenprinting ink prepared by uniformly mixing and stirring 15 parts of afluorescent pink pigment, 50 parts of an acrylic-ester emulsion, 3 partsof a water-based ink thickening agent, 0.5 parts of a leveling agent,0.3 part of an anti-foaming agent and 5 parts of a blocked-isocyanatetype cross-linking agent was applied by solid-printing using a 120-meshscreen plate, followed by drying at 130° C. for 5 minutes to harden toform a colored layer 5.

[0069] Next, on the colored layer 5, a white screen printing inkprepared by uniformly mixing and stirring 15 parts of wet-processfine-particle silicic acid (trade name: NIPSIL E-220; available fromNippon Silica Industrial Co., Ltd.), 45 parts of a urethane emulsion(trade name: HYDRAN AP-10; available from Dainippon Ink & Chemicals,Incorporated; solid content: 30%), 40 parts of water, 0.5 part of asilicone type anti-foaming agent, 3 parts of a water-based inkthickening agent, 1 part of ethylene glycol and 3 parts of ablocked-isocyanate type cross-linking agent was applied over the wholesurface by solid-printing using a 100-mesh screen plate, followed bydrying at 130° C. for 5 minutes to harden to form a porous resin layer3.

[0070] Next, from above the porous resin layer 3, a colorlesstransparent screen printing ink prepared by uniformly mixing andstirring 50 parts of a fluorine resin water repellent (trade name: NKGUARD NDN-7; available from Nikka Chemical Ind. Co., Ltd.; solidcontent: 22%), 1.5 parts of sodium alginate, 48.5 parts of water, 0.5part of a silicone type anti-foaming agent and 5 parts of ablocked-isocyanate type cross-linking agent was applied using a 100-meshscreen plate to print a star-shaped pattern, followed by drying at 170°C. for 2 minutes to harden to form a star-shaped pattern water-repellentresin layer 4 in the porous resin layer 3, thus a water-metachromaticcloth (water-metachromatic laminate) 1 was obtained (see FIG. 1).

[0071] In the water-metachromatic cloth 1, the porous resin layer 3 iswhite in the normal condition (water-unabsorbed state) and thewater-repellent resin layer 4 itself is colorless and transparent.Hence, the star-shaped pattern image formed by the both layers standingco-existent has a white color and is in the state of a latent image (seeFIG. 6A).

[0072] Water was sprayed on the surface of the water-metachromatic cloth1, whereupon the water-repellent resin layer 4 repelled the water anddid not absorb it, and the porous resin layer 3 other than the part ofthe water-repellent resin layer 4 (a star-shaped pattern) absorbed thewater to become transparent, so that a vivid fluorescent pink colorattributable to the underlying colored layer 5 became visible. Thus, awhite star-shaped pattern 4 and a background 5 with a fluorescent pinkcolor appeared (see FIG. 6B).

[0073] In the state where the water had adhered, the cloth had the aboveaspect. Upon evaporation of the water therefrom, however, its wholesurface again turned white and the star-shaped pattern 4 returned to thestate of a latent image (FIG. 6A).

Example 2

[0074] See FIGS. 2, 7A and 7B

[0075] As a support 2, a white broad cloth of polyester and cotton(65%:35%) mixed yarn was used, and the same fluorescent pink screenprinting ink as that in Example 1 was applied thereon by solid-printingusing a 120-mesh screen plate, followed by drying at 130° C. for 5minutes to harden to form a colored layer 5.

[0076] Next, on the colored layer 5, the same white screen printing inkas that in Example 1 was applied over the whole surface bysolid-printing using a 100-mesh screen plate, followed by drying at 130°C. for 5 minutes to harden to form a porous resin layer 3.

[0077] Next, on the porous resin layer 3, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 50 parts of afluorine resin water repellent (trade name: NK GUARD NDN-7; availablefrom Nikka Chemical Ind. Co., Ltd.; solid content: 22%), 1.5 parts ofsodium alginate, 48.5 parts of water, 0.5 part of a silicone typeanti-foaming agent and 5 parts of a blocked-isocyanate typecross-linking agent was applied using a 100-mesh screen plate to print astar-shaped blank pattern, followed by drying at 170° C. for 2 minutesto harden to form a water-repellent resin layer 4 (star-shaped blankpattern) in the porous resin layer 3, thus a water-metachromatic cloth(water-metachromatic laminate) 1 was obtained (see FIG. 2).

[0078] In the water-metachromatic cloth 1, the porous resin layer 3 iswhite in the normal condition (water-unabsorbed state) and thewater-repellent resin layer 4 itself is colorless and transparent.Hence, the whole surface stands white and the star-shaped pattern is inthe state of a latent image (see FIG. 7A).

[0079] Water was sprayed on the surface of the water-metachromatic cloth1, whereupon the water-repellent resin layer 4 repelled the water anddid not absorb it, and the porous resin layer 3 other than the part ofthe water-repellent resin layer 4 absorbed the water to becometransparent, so that a vivid fluorescent pink color attributable to theunderlying colored layer 5 became visible. Thus, a fluorescent pinkstar-shaped pattern (colored layer 5) and a white background(water-repellent resin layer 4) appeared (FIG. 7B).

[0080] In the state where the water had adhered, the cloth had the aboveaspect. Upon evaporation of the water therefrom, however, its wholesurface again turned white and the star-shaped pattern returned to thestate of a latent image (FIG. 7A).

Example 3

[0081] No Figure

[0082] As the support, on a white polyester tropical cloth having beensubjected to water-repellent treatment, a fluorescent pink screenprinting ink prepared by uniformly mixing and stirring 15 parts of afluorescent pink pigment, 50 parts of an acrylic-ester emulsion, 3 partsof a water-based ink thickening agent, 0.5 parts of a leveling agent,0.3 part of an anti-foaming agent and 5 parts of an epoxy typecross-linking agent was applied over the whole surface by solid-printingusing a 120-mesh screen plate, followed by drying at 100° C. for 5minutes to harden to form a colored layer with a fluorescent pink color.

[0083] Next, on the colored layer, a blue screen printing ink preparedby uniformly mixing and stirring 15 parts of wet-process fine-particlesilicic acid (trade name: NIPSIL E-1009; available from Nippon SilicaIndustrial Co., Ltd.), 5 parts of a blue pigment (trade name: SANDYESUPER BLUE GLL; available from Sanyo Color Works, Ltd.), 45 parts of aurethane emulsion (trade name: HYDRAN AP-20; available from DainipponInk & Chemicals, Incorporated; solid content: 35%), 40 parts of water,0.5 part of a silicone type anti-foaming agent, 3 parts of a water-basedink thickening agent, 1 part of ethylene glycol and 3 parts of ablocked-isocyanate type cross-linking agent was applied bysolid-printing using a 100-mesh screen plate, followed by drying at 130°C. for 5 minutes to harden to form a porous resin layer which was paleblue in the normal condition.

[0084] Next, on the porous resin layer, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 50 parts of afluorine resin water repellent (trade name: ASAHI GUARD LD-6015;available from Meisei Chemical Works, Ltd.; solid content: 15%), 3 partsof a water-based ink thickening agent, 47 parts of water, 0.5 part of asilicone type anti-foaming agent and 5 parts of a blocked-isocyanatetype cross-linking agent was applied using a 120-mesh screen plate toprint a flower-shaped pattern formed of halftone dots, followed bydrying at 170° C. for 2 minutes to harden to form a flower-shapedpattern water-repellent resin layer in the porous resin layer, thus awater-metachromatic cloth was obtained.

[0085] In the water-metachromatic cloth, the porous resin layer was paleblue in the normal condition (water-unabsorbed state) and thewater-repellent resin layer was colorless and transparent. Hence, thewhole had a pale blue aspect. Upon immersion in water, however, theporous resin layer other than the co-existent part of thewater-repellent resin layer absorbed the water to become transparent, sothat a violet color which was a mixed color of the fluorescent pinkcolor of the underlying colored layer and the blue color of the porousresin layer became visible. Thus, a flower-shaped pattern presented bypale blue halftone dots was seen on the background with a violet color.

[0086] In the state where the porous resin layer had adsorbed water, thecloth had the above aspect. Upon evaporation of the water therefrom tobecome dry, however, its whole surface returned to the original paleblue color, and such changes in aspects were repeatedly reproducible.

Example 4

[0087] No Figure

[0088] As a support, on the whole surface of a red PET (polyethyleneterephthalate) film (thickness: 100 μm), a white screen printing inkprepared by uniformly mixing and stirring 15 parts of wet-processfine-particle silicic acid (trade name: NIPSIL E-1011; available fromNippon Silica Industrial Co., Ltd.), 45 parts of a urethane emulsion(trade name: NEOREZ R-966; available from Abishia K. K.; solid content:33%), 40 parts of water, 0.5 part of a silicone type anti-foaming agent,3 parts of a water-based ink thickening agent, 1 part of ethylene glycoland 3 parts of a blocked-isocyanate type cross-linking agent was appliedby solid-printing using a 80-mesh screen plate, followed by drying at130° C. for 5 minutes to harden to form a porous resin layer.

[0089] Next, on the porous resin layer, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 50 parts of asilicone resin water repellent (trade name: SM8707; available from DowCorning Toray Silicone Co., Ltd.; solid content: 40%), 3 parts ofpolyethylene oxide, 47 parts of water and 5 parts of a metal typecatalyst was applied using a 100-mesh screen plate to print a polka-dotpattern, followed by drying at 150° C. for 5 minutes to harden to form apolka-dot pattern water-repellent resin layer in the porous resin layer,thus a water-metachromatic film (water-metachromatic laminate) wasobtained.

[0090] The water-metachromatic film had a white color over the whole inthe normal condition. Upon immersion in water, however, the the porousresin layer other than the co-existent part of the water-repellent resinlayer absorbed the water to become transparent, so that a red color ofthe support itself became visible. Thus, a white polka-dot pattern wasseen on the background with a red color.

[0091] In the state where the porous resin layer had adsorbed water, thefilm had the above aspect. Upon evaporation of the water therefrom tobecome dry, however, its whole surface returned to the original whitecolor, and such changes in aspects were repeatedly reproducible.

Example 5

[0092] See FIGS. 3, 8A and 8B

[0093] On a support 2 comprised of a white polyester tricot cloth, agreen screen printing ink prepared by uniformly mixing and stirring 5parts of a green pigment, 45 parts of an acrylic-ester emulsion, 0.5part of a silicone type anti-foaming agent, 3 parts of a water-based inkthickening agent, 10 parts of water and 5 parts of a blocked-isocyanatetype cross-linking agent was applied by solid-printing using a 150-meshscreen plate, followed by drying at 130° C. for 5 minutes to harden toform a colored layer 5 with a green color.

[0094] Next, on the colored layer 5, a white screen printing inkprepared by uniformly mixing and stirring 15 parts of wet-processfine-particle silicic acid (trade name: NIPSIL E-200; available fromNippon Silica Industrial Co., Ltd.), 45 parts of a urethane emulsion(trade name: HYDRAN AP-20; available from Dainippon Ink & Chemicals,Incorporated; solid content: 33%), 40 parts of water, 0.5 part of asilicone type anti-foaming agent, 3 parts of a water-based inkthickening agent, 1 part of ethylene glycol and 3 parts of ablocked-isocyanate type cross-linking agent was applied bysolid-printing using a 80-mesh screen plate to print a heart-shapedpattern, followed by drying at 130° C. for 5 minutes to harden to form aporous resin layer 3.

[0095] Next, on the porous resin layer 3, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 60 parts of afluorine resin water repellent (trade name: LIFE GUARD FR-448; availablefrom Kyoeisha Chemical Co., Ltd.; solid content: 30%), 45 parts ofwater, 5 parts of polyvinyl alcohol and 0.5 part of a silicone typeanti-foaming agent was applied using a 100-mesh screen plate to print analphabet letter “A”, followed by drying at 170° C. for 2 minutes toharden to form a water-repellent resin layer 4 in the porous resin layer3, thus a water-metachromatic cloth 1 was obtained (see FIG. 3).

[0096] Using the water-metachromatic cloth 1, a swimming suit of a dollwas sewed to obtain a water-metachromatic toy-doll swimming suit.

[0097] In the water-metachromatic toy-doll swimming suit, the whiteheart-shaped pattern of the porous resin layer is seen with the greencolored layer 5 for the background in the normal condition (FIG. 8A).

[0098] The swimming suit was made wet with water, whereupon the partother than the water-repellent resin layer 4 (the letter “A”) existingin the white heart-shaped pattern became transparent, so that a greencolor became visible. Thus, the letter “A” was seen white (FIG. 8B).

[0099] The above aspect was retained when the porous resin layer was inthe water-absorbed state. Upon evaporation of the water therefrom tobecome dry, however, the white heart-shaped pattern again becamevisible. Such changes in aspects were interchangeable, and wererepeatedly reproducible.

Example 6

[0100] See FIGS. 4, 9A and 9B

[0101] On a white polyester tricot cloth (support 2), a fluorescentorange screen printing ink prepared by uniformly mixing and stirring 10parts of a fluorescent orange pigment, 45 parts of an acrylic-esteremulsion, 0.5 part of a silicone type anti-foaming agent, 3 parts of awater-based ink thickening agent, 10 parts of water and 5 parts of ablocked-isocyanate type cross-linking agent was applied bysolid-printing using a 150-mesh screen plate, followed by drying at 130°C. for 5 minutes to harden to form a colored layer 5 with a fluorescentorange color.

[0102] Next, on the colored layer 5, a white screen printing inkprepared by uniformly mixing and stirring 15 parts of wet-processfine-particle silicic acid (trade name: NIPSIL E-200; available fromNippon Silica Industrial Co., Ltd.), 45 parts of a urethane emulsion(trade name: HYDRAN AP-10; available from Dainippon Ink & Chemicals,Incorporated; solid content: 30%), 40 parts of water, 0.5 part of asilicone type anti-foaming agent, 3 parts of a water-based inkthickening agent, 1 part of ethylene glycol and 3 parts of ablocked-isocyanate type cross-linking agent was applied bysolid-printing using a 80-mesh screen plate to print a heart-shapedpattern, followed by drying at 130° C. for 5 minutes to harden to form aporous resin layer 3.

[0103] Next, on the porous resin layer 3, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 45 parts of afluorine resin water repellent (trade name: ASAHI GUARD AG-480;available from Meisei Chemical Works, Ltd.; solid content: 20%), 45parts of water, 5 parts of a water-based ink thickening agent and 0.5part of a silicone type anti-foaming agent was applied using a 100-meshscreen plate to print a heart-shaped pattern a little larger than theporous resin layer 3 (heart-shaped pattern), having at its central areaa blank pattern of an alphabet letter “A”, followed by drying at 170° C.for 2 minutes to harden to form a water-repellent resin layer 4, thus awater-metachromatic cloth 1 was obtained (see FIG. 4).

[0104] Using the water-metachromatic cloth 1, a swimming suit of a dollwas sewed to obtain a water-metachromatic toy-doll swimming suit.

[0105] In the water-metachromatic toy-doll swimming suit, the whiteheart-shaped pattern is seen with the fluorescent orange colored layer 5for the background in the normal condition (FIG. 9A).

[0106] The swimming suit was made wet with water, whereupon only theletter “A” became transparent, so that the white heart-shaped patternbecame visible (FIG. 9B).

[0107] The above aspect was retained when the porous resin layer was inthe water-absorbed state. Upon evaporation of the water therefrom tobecome dry, however, it returned to the aspect of the white heart-shapedpattern again. Such changes in aspects were interchangeable, and wererepeatedly reproducible.

Example 7

[0108] No Figure

[0109] As a support, on a white broad cloth of polyester and cotton(65%:35%) mixed yarn, a reversible thermochromic screen printing inkprepared by uniformly mixing and stirring 30 parts of a reversiblethermochromic microcapsule pigment capable of turning colorless at 30°C. or above and turning blue at 28° C. or below, 5 parts of afluorescent pink pigment, 50 parts of an acrylic-resin emulsion, 1 partof an anti-foaming agent, 4 parts of a water-based ink thickening agent,15 parts of water and 5 parts of a blocked-isocyanate type cross-linkingagent was applied by solid-printing using a 120-mesh screen plate,followed by drying at 130° C. for 5 minutes to harden to form areversible thermochromic colored layer 5 capable of turning bluishviolet at 30° C. or above and turning fluorescent pink at 28° C. orbelow.

[0110] Next, on the reversible thermochromic colored layer, a whitescreen printing ink prepared by uniformly mixing and stirring 15 partsof wet-process fine-particle silicic acid (trade name: NIPSIL E-220;available from Nippon Silica Industrial Co., Ltd.), 45 parts of aurethane emulsion (trade name: HYDRAN AP-10; available from DainipponInk & Chemicals, Incorporated; solid content: 30%), 40 parts of water,0.5 part of a silicone type anti-foaming agent, 3 parts of a water-basedink thickening agent, 1 part of ethylene glycol and 3 parts of ablocked-isocyanate type cross-linking agent was applied over the wholesurface by solid-printing using a 100-mesh screen plate, followed bydrying at 130° C. for 5 minutes to harden to form a porous resin layer.

[0111] Next, on the porous resin layer, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 50 parts of afluorine resin water repellent (trade name: NK GUARD NDN-7; availablefrom Nikka Chemical Ind. Co., Ltd.; solid content: 22%), 1.5 parts ofsodium alginate, 48.5 parts of water, 0.5 part of a silicone typeanti-foaming agent and 5 parts of a blocked-isocyanate typecross-linking agent was applied using a 100-mesh screen plate to print astar-shaped pattern, followed by drying at 170° C. for 2 minutes toharden to form a star-shaped pattern water-repellent resin layer so asto exist in the porous resin layer, thus a water-metachromatic cloth wasobtained.

[0112] The water-metachromatic cloth had a white color over the wholesurface in the normal condition (water-unabsorbed state). Water of 24°C. was sprayed on the surface of the cloth to make it wet, whereupon thewater-repellent resin layer repelled the water and did not absorb it tostand white. On the other hand, the porous resin layer absorbed thewater to become transparent, so that a bluish violet color attributableto the underlying reversible thermochromic colored layer was seenthrough and the background white star-shaped pattern became visible.Thereafter, upon evaporation of the water to become dry, its wholesurface returned to the aspect of white color.

[0113] The water-metachromatic cloth was also immersed in warm water of40° C., whereupon, in addition to the above changes in aspects, thereversible thermochromic colored layer changed from a blue color to afluorescent pink color, and the white star-shaped pattern became visibleon the background with a fluorescent pink color. It was taken out of thewarm water and was left at about 20° C. room temperature, whereupon thebackground with a fluorescent pink color turned blue, and, withevaporation of the water to become dry, the whole surface again turnedwhite. Such changes in aspects were repeatedly interexchangeablyreproduced.

Example 8

[0114] No Figure

[0115] As a support, on a white polyester tricot cloth, a reversiblethermochromic screen printing ink prepared by uniformly mixing andstirring 30 parts of a reversible thermochromic microcapsule pigmentcapable of turning colorless at 30° C. or above and turning pink at 28°C. or below, 50 parts of an acrylic-resin emulsion, 1 part of ananti-foaming agent, 5 parts of a water-based ink thickening agent, 10parts of water and 5 parts of an ethylene-imine type cross-linking agentwas applied by solid-printing using a 100-mesh screen plate, followed bydrying at 100° C. for 5 minutes to harden to form a reversiblethermochromic colored layer.

[0116] Next, on the reversible thermochromic colored layer, a whitescreen printing ink prepared by uniformly mixing and stirring 15 partsof wet-process fine-particle silicic acid (trade name: NIPSIL E-200;available from Nippon Silica Industrial Co., Ltd.), 45 parts of aurethane emulsion (trade name: HYDRAN AP-20; available from DainipponInk & Chemicals, Incorporated; solid content: 33%), 40 parts of water,0.5 part of a silicone type anti-foaming agent, 3 parts of a water-basedink thickening agent, 1 part of ethylene glycol and 3 parts of ablocked-isocyanate type cross-linking agent was applied bysolid-printing using a 80-mesh screen plate, followed by drying at 130°C. for 5 minutes to harden to form a porous resin layer.

[0117] Next, on the porous resin layer, a colorless transparent screenprinting ink prepared by uniformly mixing and stirring 60 parts of afluorine resin water repellent (trade name: LIFE GUARD FR-448; availablefrom Kyoeisha Chemical Co., Ltd.; solid content: 30%), 45 parts ofwater, 5 parts of polyvinyl alcohol and 0.5 part of a silicone typeanti-foaming agent was applied using a 100-mesh screen plate to print analphabet letter “A”, followed by drying at 170° C. for 2 minutes toharden to form a water-repellent resin layer in the porous resin layer,thus a water-metachromatic cloth was obtained.

[0118] The water-metachromatic cloth was cut and sewed to obtain awater-metachromatic toy-doll swimming suit. In this swimming suit, thepink color of the reversible thermochromic colored layer and the whiteheart-shaped pattern of the porous resin layer stood visible in thenormal condition. The swimming suit was made wet with water of 24° C.,whereupon the white heart-shaped pattern became transparent and changedinto the pink color of the reversible thermochromic colored layer, andonly the letter “A” became visible on the pink-color background. Uponevaporation of the water the porous resin layer had absorbed, swimmingsuit returned to the aspect of the white heart-shaped pattern on thepink-color background.

[0119] The water-metachromatic toy-doll swimming suit was also immersedin warm water of 40° C., whereupon the porous resin layer absorbed thewater to become transparent and the reversible thermochromic coloredlayer also changed simultaneously from a pink color to become colorless,where the whole surface became white. It was taken out of the warm waterand was left at about 20° C. room temperature, whereupon only the letter“A” became visible in white on the pink-color background from the stateof the whole surface being white. Upon evaporation of the water from thecloth, the white heart-shaped pattern again appeared on the pink-colorbackground. Such changes in aspects were repeatedly interexchangeablyreproduced.

Example 9

[0120] See FIGS. 5, 10A and 10B

[0121] On a support 2 comprised of a white polyester satin cloth, agreen screen printing ink was applied by solid-printing using a 120-meshscreen plate, followed by drying at 130° C. for 5 minutes to harden toform a colored layer 5.

[0122] Next, on the colored layer 5, the same white screen printing inkas that in Example 1 was applied over the whole surface bysolid-printing using a 100-mesh screen plate, followed by drying at 130°C. for 5 minutes to harden to form a porous resin layer 3.

[0123] Next, on the porous resin layer 3, the same colorless transparentscreen printing water-repelling ink as that in Example 1 was appliedusing a 100-mesh screen plate to print a star-shaped blank pattern,followed by drying at 170° C. for 2 minutes to harden to form astar-shaped blank pattern (water-repellent resin layer 4) in the porousresin layer 3. Thereafter, using the same fluorescent pink screenprinting ink as that in Example 1, a heart-shaped blank pattern having aspace large enough to allow the star-shaped blank pattern to existtherein (on its surrounding, the pink-color colored layer 51 was formed)was printed making registration (positional adjustment) so that thestar-shaped blank pattern existed therein, thus a water-metachromaticcloth (water-metachromatic laminate) 1 was obtained (see FIG. 5).

[0124] In the water-metachromatic cloth 1, the white heart-shapedpattern (attributable to the porous resin layer 3) was seen with thepink color (colored layer 51) for the background in the normal condition(water-unabsorbed state). Water was sprayed thereon to make it wet,whereupon a green star-shaped pattern (colored layer 5) appeared fromthe inside of the white heart-shaped pattern. The cloth had this aspectwhen it was kept wet, but once it became dry, the green star-shapedpattern disappeared and changed into the white heart-shaped pattern toreturn to the original state (see FIGS. 10A and 10B).

[0125] The above changes in aspects were repeatedly reproducible.

[0126] As described above, according to the water-metachromatic laminateof the present invention, latent images standing invisible in the normalcondition can be rendered visible as colored images by means of water asa medium. Especially on account of the effects attributable to both theco-existence of the water-repellent resin layer (image) and thelayer-by-layer printing, a variety of images can interchangeably be madeto be seen. Thus, new utility as a toy and unexpectedness,decorativeness and detectability can be imparted so that the product isapplicable to a variety of fields of toys, doll clothing, teachingmaterials, picture books, picture coloring, artificial flowers,swimsuit, umbrellas, rainware and so forth.

[0127] Moreover, the application of the production process of thepresent invention enables simple formation of any desired images by thewater-repellent resin layer which is formed by a printing means in thestate it is existent in and co-existent with the porous resin layer.

What is claimed is:
 1. A water-metachromatic laminate comprising asupport and superposingly provided thereon i) a porous resin layer whichis formed of a binder resin to which a low-refractive-index pigmentstands fixed dispersedly, and is opaque in a water-unabsorbed state andcapable of turning transparent in a water-absorbed state and ii) awater-repellent resin layer so provided as to exist in the porous resinlayer at its some area or areas in a co-existent state; the porous resinlayer being so made up that its area or areas not provided with thewater-repellent resin layer turn(s) transparent in a water-absorbedstate so that the both layers are visually distinguishable.
 2. Thewater-metachromatic laminate according to claim 1, wherein at least oneof the porous resin layer and the water-repellent resin layer comprisesany image or images selected from a letter, a mark or sign, an Arabic orRoman numeral, a spot, a line and a design.
 3. The water-metachromaticlaminate according to claim 1, wherein a first colored layer is providedbetween the surface of the support and the porous resin layer.
 4. Thewater-metachromatic laminate according to claim 1, wherein a secondcolored layer is provided on the water-repellent resin layer.
 5. Thewater-metachromatic laminate according to claim 4, wherein the secondcolored layer comprises any image or images selected from a letter, amark or sign, an Arabic or Roman numeral, a spot, a line and a design.6. The water-metachromatic laminate according to claim 1, wherein thelow-refractive-index pigment comprises a fine-particle silicic acid andthe binder resin is selected from urethane resins.
 7. Thewater-metachromatic laminate according to claim 1 or 6, wherein thelow-refractive-index pigment comprises a fine-particle silicic acidproduced by a wet process and is formulated in the porous resin layer ina proportion of from 1 to 30 g/m².
 8. The water-metachromatic laminateaccording to claim 1, wherein the support comprises a cloth.
 9. Thewater-metachromatic laminate according to claim 8, wherein the cloth hasbeen made water-repellent.
 10. A process for producing awater-metachromatic laminate, comprising the steps of; providing aporous resin layer on a support; and thereafter applying onto the porousresin layer a water-repelling solution containing a water-repellentresin, by a printing, coating, spraying, writing or stamping means tomake the water-repelling solution adhere to the porous resin layer andpenetrate thereinto; followed by drying to form a water-repellent resinlayer existing in the porous resin layer in a co-existent state.